CHRISTOPHER: Well, [Max] and I never met. I didn’t even know he existed until late in the game. Hell, I didn’t even know you were engaged until you called me from your bachelorette party. And I wasn’t invited to the wedding – or did my invitation get lost in the mail?
LORELAI: Well, you’ve moved a lot this past year.
Lorelai and Max’s relationship moved extremely quickly and they had a significant break from it. When they got back together, they got engaged almost immediately. In fact, Lorelai only seems to call Christopher from her bachelorette party in hopes of getting talked out of it (in which case, mission accomplished).
It is interesting she never told Christopher though, considering that she was going right through her address book to tell distant relatives and the man who did her shower that she and Max were back together. Maybe she didn’t want to get talked out of it that soon. I suspect if she had sent him an invitation, it would have gone to the wrong address, and he would’ve been a no-show (again).
Christopher is getting awfully huffy about this neglect, but by the time Lorelai phones him to say she is getting married, we find out later he is already with Sherry – something which he hid from Lorelai. It looks very much as if Lorelai’s news pushed him into committing Sherry faster than he otherwise would have.